• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.624-630
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• 2007

The dynamic window approach(DWA) is a well known technique for reactive collision avoidance. It shows safe and efficient performance in real-world experiments. However, a robot can get stuck in local minima because no information about the connectivity of the free space is used to determine the motion. The global DWA can solve this problem of local minima by adding a navigation function. Even with the global DWA, it is still difficult for a robot to execute an abrupt change in its direction, for example, entering from the corridor to a doorway. This paper proposes a modified global DWA using the included angles of waypoints extracted from an optimal path. This scheme enables the robot to decelerate in advance before turning into the doorway. Therefore the robot can reach the goal position more safely and efficiently at high speeds.

• Journal of KIISE:Information Networking
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• v.33 no.5
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• pp.369-379
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• 2006

In recent years, there have been many researches about Ad-hoc Networks which is available to communicate freely between mobile devices by using multi-hop without any support of relay base or access point. TCP that used the most widely transport protocol in the Internet repeats packet loss and retransmission because it increases congestion window size by using reactive congestion control until packet loss occurs. As a result of this, energy of mobile device is wasted unnecessarily. In this paper, we propose TCP-New Veno in order to improve the energy efficiency of mobile device. According to the state of network, the scheme adjusts appropriate size of congestion window. Therefore, the energy efficiency of mobile device and utilization of bandwidth are improved by the scheme. From the simulation by using ns-2, we could see more improved energy efficiency with TCP-New Veno than those with TCP in Ad-hoc Networks.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.91-100
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• 2004

This paper presents a receiver-driven TCP flow control mechanism, which is adaptive to the wireless condition, for memory constrained mobile receiver. A receiver-driven TCP flow control is, in general, achieved by adjusting the size of advertised window at the receiver. The proposed method constantly measures at the receiver both the available wireless bandwidth and the packet round-trip time. Depending on the measured values, the receiver adjusts appropriately the size of advertised window. Constrained by the adjusted window which reflects the current state of the wireless network, the sender achieves an improved TCP throughput as well as the reduced round-trip packet delay. Its implementation only affects the protocol stack at the receiver and hence neither the sender nor the router are required to be modified. The mechanism has been implemented in real environments. The experimental results show that in CDMA2000 1x networks the TCP throughput of the proposed method has improved about 5 times over the conventional method when the receiver's buffer size is limited to 2896 bytes. Also, with 64Kbytes of buffer site, the packet round-trip time of the proposed method has been reduced in half, compared the case with the conventional method.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.71-76
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• 2019

In this paper, we propose a simple one-click marketing solution for mobile devices which can advertise a product which is embedded in a mobile video while watching the video on a smartphone. If a specific product of interest appears in the video to the user, one can simply click on the product in the video and a pop-up window with information about the product is proposed. The implementation of the system is expected to enable users to gain real-time information about the product while watching the video without having to search for the product again after watching the movie, and thereby facilitating more mobile commerce. We use a two-fold system to prevent the failure of tracking which often occurs on a single online tracking system, so that the user cannot always get the commercial product information.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.126-129
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• 2007

Recently the use of wireless network increases according to it solves the hand-off and with path loss, pading, noise etc of wireless network the research for transmission error improvement is developed. TCP and SCTP of standard where it guarantees the reliability of wire network apply in wireless network the congestion control, flow control mechanism used it decreases the efficiency of data transfer throughputs. In this paper, It mixes SCTP and SNOOP for SCTP apply on wireless network, to improve BS(Basic Station) operation processes when the transmission error occurs in wireless network. BS send ZWP(Zero Window Probe) to MN(Mobile Node) when the transmission error occurs so, check path and status and update RWND and error status checked. It selects the new path, send ZWA(Zero Window Advertisement) to FH(Fixed Host) and the prevents call to congestion control or flow control and it does to make wait status standing. Continuously of data transfer after the connection of wireless network is stabilized, it make increase about 10% the transmission throughput of data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.429-432
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• 2012

Mobile devices diffusion begins by the iPhone and spreads by the Android. A widely used mobile devices is Smartphone(iPhone, Android, Bada, WindowPhone7, BlackBerry, etc) and Tablet(iPad, Android). In the past, we have developed a dedicated application for device. But, Now we must develop a application by considering the characteristics of the operating system. Accordingly, many problems occurred and other developmet methods have emerged. In this paper, we learn about MobileHybridApp development tool-oriented One Source Multi Use-and compare the differences, propose a method to develop context-sensitive.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.227-234
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• 2006

In this paper, we propose a window based resource reservation scheme to minimize an waste bandwidth due to resource reservation in mobile networks. Specially, this scheme decides a proper timing to reserve resource by using the number of movement, which is provided by the differentiated handoff estimation model, among inner regions. In the previous resource reservation scheme[6], it requests a resource reservation to neighboring cells as soon as a mobile host enters or creates into a cell. But, after a proper time based on the number of movements in the differentiated handoff estimation model passes, the proposed scheme requests a resource reservation to neighboring cells. Because of this reason, it can improve resource utilization on mobile networks. And, this scheme differentiates resource reservation according to a request ratio for resource reservation to each neighboring cell. Also, this scheme improves resource reservation acceptance rate and bandwidth utilization.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.31-41
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• 2006

Internet access from mobile phones over cellular networks suffer from severe bandwidth limitations and high bit error rates over wireless access links. Tailoring TCP connections to best fit the characteristics of this bottleneck link is thus very important for overall performance improvement. In this work, we propose a simple algorithm in deciding the optimal TCP segment size to maximize the utilization of the bottleneck wireless TCP connection for mobile contents server access, taking the dynamic TCP window variation into account. The proposed algorithm can be used when the product of the access rate and the propagation time is not large. With some numerical examples, it is shown that the optimal TCP segment size becomes a constant value when the TCP window size exceeds a threshold. One can set the maximum segment size of a wireless TCP connection to this optimal segment size for mobile contents server access for maximum efficiency on the expensive wireless link.

• Fashion & Textile Research Journal
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• v.18 no.2
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• pp.158-166
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• 2016

This study investigates the impact of fashion product attributes and mobile shopping mall attributes on impulse buying behavior and mobile shopping satisfaction. The findings provide new information to marketers on marketing strategy for mobile shopping malls. We obtained 283 usable questionnaires from college students. Data were analyzed by frequency analysis, correlation analysis, factor analysis using SPSS for Window 21.0 and confirmatory factor analysis and structural equation model analysis by AMOS 21.0. The results were as follows. The utility of fashion products attributes had the greatest impact on impulse buying behavior when buying fashion products in a mobile mall. Utility had a negative effect on impulsive buying behavior and exhibitionistic had a positive effect on impulsive buying behavior. Next, continuous management of mobile shopping mall attributes influenced impulse buying behavior. In addition, impulse buying behavior showed that the positive effect on satisfaction. Fashion product attributes had a greater impact on impulsive buying behavior than mobile mall properties when buying fashion products in the mobile mall; in addition, impulse buying facilitated customer satisfaction.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.28-28
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• 2004